1. Field of the Invention
This invention pertains generally to wireless communication and, more particularly, to wireless nodes employing an energy store for power. The invention also pertains to methods of powering wireless nodes and, more particularly, of charging an energy store responsive to ambient light.
2. Background Information
Relatively low power, radio frequency (RF) lighting control systems employ wall-mounted, battery powered, RF switch “sensors”. Such a switch sensor sends a signal to a remote power control device, such as relay, in order to turn one or more lights on and off. Since the switch sensors are battery powered, the batteries must either be manually replaced or else must be recharged from a suitable power source.
Unlike stand-alone devices, a low power, RF sensor device allows its sensor to be connected to a remote controller or monitor.
It is known to provide a sensor system in which a plurality of sensors are connected, either directly with wires or indirectly with RF communications, to a central control and monitoring device. An example of such a sensor system is a security system, which may include a telephone line for dial out/in communication.
U.S. Pat. No. 5,883,577 discloses a smoke detection unit including a solar cell array and first and second trickle charger/voltage regulator adjustable units. Power from the solar cell array is gained from light sources in the home or factory. The solar cell array provides up to 9 volts to the smoke detector unit via the first trickle charger with ambient light.
U.S. Pat. No. 6,340,864 discloses a wireless remote sensor employing low-power CMOS circuit techniques. Since the power requirements are so low, the sensor can maintain operation via a power source using only electromagnetic radiation, i.e., “free” power, which emanates from ambient energy sources. The sensor may receive “free” power from ambient energy sources and also includes a battery backup. In this embodiment, the power source provides power to the sensor to operate using the “free” power and/or the battery supplied power. This allows the sensor to conserve the battery energy level by using the “free” power when possible.
It is known to employ a wide range of electronic devices that are solar powered for outdoor use.
It is known to power a hand-held calculator by collecting and storing power derived from artificial indoor light.
There is room for improvement in wireless nodes and in methods of powering wireless nodes employing ambient light to charge an energy store.